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Cadillac 45 V8 specs: 273 ci (4.5L) 8-cylinder, 3.622 x 3.307 in (92 x 84 mm) bore and stroke, 9:1 compression. Rated 180 hp. OHV. Rod ratio and piston speed.
The Cadillac 45 V8 is oversquare — the 3.622" bore exceeds the 3.3071" stroke by 9.5% — a layout that favors airflow and RPM over leverage at the crank. The 3.3071" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 34.1 ci (559 cc).
9:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the HT4100 family, sitting between the 250 ci and 300 ci members. Factory fitments include the Cadillac DeVille, Cadillac Eldorado, Cadillac Seville and 3 others.
| Displacement | 273 ci / 4.5 L |
|---|---|
| Bore | 3.622" |
| Stroke | 3.3071" |
| Cylinders | 8 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 1.095 |
| Block material | aluminum |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 180 hp |
| Bore/stroke character | 1.095 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,307 ft/min — conservative for a street engine |
| Displacement per cylinder | 34.1 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
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